1. Field of the Invention
The present invention relates to a robot system, more particularly, to a robot system to identify a location of a mobile robot by receiving light including phase information from beacons.
2. Description of the Related Art
As robots are getting more widely used in various fields of industries, various robots that perform different functions are being developed, for example, a robot to manage household duties, etc. In the past, robots were confined to a space, and performed an assigned task. However, today, robots can automatically move and operate beyond a predetermined orbit.
In order to move a mobile robot to a target location, various techniques have been proposed, such as, detecting a guide line or providing a device on a moving path, etc.
FIG. 1 schematically illustrates a conventional robot system in which a mobile robot determines the robot's location through the use of beacons.
As shown in FIG. 1, the conventional robot system comprises beacons 100, and a mobile robot 110.
The beacon 100 includes a plurality of transmitters 101 placed at predetermined positions emitting light such as an infrared ray, an electromagnetic wave, or the like, which travels in a straight line.
Because the light emitted from the transmitters 101 travels in a straight line, the light reaches the mobile robot 110 when the mobile robot 110 is located within a predetermined area aligned with the transmitters 101. Further, each transmitter 101 emits light different from the light emitted by the other transmitters in inherent information.
The mobile robot 110 includes a plurality of receivers 111, and a controller (not shown).
The receiver 111 receives the light emitted from the transmitter 101 of the beacon 100, and outputs information based on intensity of the received light to the controller.
The controller determines the position of the beacon 100 based on intensity information outputted by the receiver 111, and determines a location of the mobile robot 110 relative to the position of the beacon 100.
A method of identifying the location of the mobile robot 110 according to the conventional robot system will be further described in the following paragraphs.
While moving, the mobile robot 110 continuously receives the light emitted from the transmitter 101 of the beacon 100 through the plurality of receivers 111. Accordingly, the farther the light emitted from the transmitter 101 travels in a straight line, the more the light becomes diffused. Therefore, the light received by the receiver 111 has maximum intensity when the receiver 111 and the transmitter 101 are aligned.
The receiver 111 outputs information based on the intensity of the received light to the controller, and the controller determines the relative position of the beacon 100 based on the intensity information outputted by the receiver 111.
Light received by the receivers 111 does not have an interference because the light travels in a straight line, and includes the inherent information of the respective transmitter 101 provided to the beacon 100, thus, allowing the controller to calculate the location of the mobile robot 110 relative to the position of the beacon 100.
However, the conventional robot system, using the beacon 100, makes use of an analog signal that is highly affected by properties of the transmitter and the receiver, making it difficult to precisely determine the intensity of the light. Further, a wave traveling in space has decreased energy inversely proportional to the cubed distance of the wave from the transmitter; therefore, the movable area of the mobile robot 110 is limited to the surrounding area of the beacon 100.
Further, a conventional robot system has been provided according to which the location of a mobile robot is determined by an image processing operation using a camera, etc. However, this operation has a relatively high cost, and is sensitive to illumination.